/**
 * Backbone localStorage Adapter
 * https://github.com/jeromegn/Backbone.localStorage
 */
(function () {
  // A simple module to replace `Backbone.sync` with *localStorage*-based
  // persistence. Models are given GUIDS, and saved into a JSON object. Simple
  // as that.
  // Hold reference to Underscore.js and Backbone.js in the closure in order
  // to make things work even if they are removed from the global namespace
  var _ = this._;
  var Backbone = this.Backbone;
  // Generate four random hex digits.

  function S4() {
    return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
  };
  // Generate a pseudo-GUID by concatenating random hexadecimal.

  function guid() {
    return (S4() + S4() + "-" + S4() + "-" + S4() + "-" + S4() + "-" + S4() + S4() + S4());
  };
  // Our Store is represented by a single JS object in *localStorage*. Create it
  // with a meaningful name, like the name you'd give a table.
  // window.Store is deprectated, use Backbone.LocalStorage instead
  Backbone.LocalStorage = window.Store = function (name) {
    this.name = name;
    var store = this.localStorage().getItem(this.name);
    this.records = (store && store.split(",")) || [];
  };
  _.extend(Backbone.LocalStorage.prototype, {
    // Save the current state of the **Store** to *localStorage*.
    save: function () {
      this.localStorage().setItem(this.name, this.records.join(","));
    },
    // Add a model, giving it a (hopefully)-unique GUID, if it doesn't already
    // have an id of it's own.
    create: function (model) {
      if (!model.id) {
        model.id = guid();
        model.set(model.idAttribute, model.id);
      }
      this.localStorage().setItem(this.name + "-" + model.id, JSON.stringify(model));
      this.records.push(model.id.toString());
      this.save();
      return model.toJSON();
    },
    // Update a model by replacing its copy in `this.data`.
    update: function (model) {
      this.localStorage().setItem(this.name + "-" + model.id, JSON.stringify(model));
      if (!_.include(this.records, model.id.toString())) this.records.push(model.id.toString());
      this.save();
      return model.toJSON();
    },
    // Retrieve a model from `this.data` by id.
    find: function (model) {
      return JSON.parse(this.localStorage().getItem(this.name + "-" + model.id));
    },
    // Return the array of all models currently in storage.
    findAll: function () {
      return _(this.records).chain().map(function (id) {
        return JSON.parse(this.localStorage().getItem(this.name + "-" + id));
      }, this).compact().value();
    },
    // Delete a model from `this.data`, returning it.
    destroy: function (model) {
      this.localStorage().removeItem(this.name + "-" + model.id);
      this.records = _.reject(this.records, function (record_id) {
        return record_id == model.id.toString();
      });
      this.save();
      return model;
    },
    localStorage: function () {
      return localStorage;
    }
  });
  // localSync delegate to the model or collection's
  // *localStorage* property, which should be an instance of `Store`.
  // window.Store.sync and Backbone.localSync is deprectated, use Backbone.LocalStorage.sync instead
  Backbone.LocalStorage.sync = window.Store.sync = Backbone.localSync = function (method, model, options, error) {
    var store = model.localStorage || model.collection.localStorage;
    // Backwards compatibility with Backbone <= 0.3.3
    if (typeof options == 'function') {
      options = {
        success: options,
        error: error
      };
    }
    var resp;
    switch (method) {
    case "read":
      resp = model.id != undefined ? store.find(model) : store.findAll();
      break;
    case "create":
      resp = store.create(model);
      break;
    case "update":
      resp = store.update(model);
      break;
    case "delete":
      resp = store.destroy(model);
      break;
    }
    if (resp) {
      options.success(resp);
    } else {
      options.error("Record not found");
    }
  };
  Backbone.ajaxSync = Backbone.sync;
  Backbone.getSyncMethod = function (model) {
    if (model.localStorage || (model.collection && model.collection.localStorage)) {
      return Backbone.localSync;
    }
    return Backbone.ajaxSync;
  };
  // Override 'Backbone.sync' to default to localSync,
  // the original 'Backbone.sync' is still available in 'Backbone.ajaxSync'
  Backbone.sync = function (method, model, options, error) {
    return Backbone.getSyncMethod(model).apply(this, [method, model, options, error]);
  };
})();